We reported an ultra low-power resistive random access memory (RRAM) combining a low-cost Ni electrode and covalent-bond GeOx dielectric. This cost-effective Ni/GeOx/TaN RRAM device has very small set power of 2 mu W, ultra-low reset power of 130 pW, greater than 1 order of magnitude resistance window, and stable retention at 85 degrees C. The current flow at low-resistance state is governed by Poole-Frenkel conduction with electrons hopping via defect traps, which is quite different from the filament conduction in metal-oxide RRAM. (C) 2011 Elsevier Ltd. All rights reserved.